In a communications system, cell capacity (throughput) and uplink/downlink coverage are two important indicators for evaluating the performance of the communications system. Cell coverage can generally be preliminarily evaluated by using a link budget, and the uplink/downlink coverage is affected by a lot of hardware performance.
For the downlink coverage, a formula for calculating its link budget may be: Maximum downlink transmission path loss=Transmit power at the top of the base station cabinet—Base station feeder loss+Base station antenna gain+Terminal antenna gain−Terminal feeder loss−Terminal receiver sensitivity−Body loss−Power margin.
For the uplink coverage, a formula for calculating its link budget may be: Maximum uplink transmission path loss=Terminal power−Terminal feeder loss+Terminal antenna gain−Body loss+Base station antenna gain−Base station feeder loss−Base station receiver sensitivity−Power margin.
As can be seen from the above, in a situation where transmit power of a base station, an antenna gain and a feeder loss of the base station, and an antenna gain and a feeder loss of a terminal are ascertained, the downlink coverage depends mainly on receiver sensitivity of the terminal, and maximum transmit power of the terminal may need to be limited to meet sensitivity requirements; and in a situation where receiver sensitivity of the base station, the antenna gain and the feeder loss of the base station, and the antenna gain and the feeder loss of the terminal are ascertained, the uplink coverage depends mainly on transmit power of the terminal. Limiting the transmit power of the terminal causes a certain contradiction between the uplink coverage and the downlink coverage.
Currently, uplink/downlink coverage of a cell is enhanced mainly by using means such as improving receiver sensitivity of a terminal by increasing transmit power of a base station, adding a tower-mounted amplifier, increasing an antenna gain, reducing a feeder loss, and improving device performance. Without exception, in all these means, hardware device deployment needs to be increased, or hardware device performance needs to be improved. This greatly increases device costs.